Compensating alternating-current dynamo



(No Model.)

I 0. B. SHALLENBERGER. COMPENSATING ALTERNATING CURRENT DYNAMO.

Patented June 14, 1892.

Fig--1.

WITNESSES: 4Q

INVENTOR,

UNITED STATES PATENT OEEIcE.

OLIVER B. SIIALLENBERGER, OF ROCHESTER, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE IVESTINGHOUSE ELECTRIC AND MANUFACTURING COM- PANY, OF PITTSBURG, PENNSYLVANIA.

COMPENSATING ALTERNATlNG-CURRENT DYNAMO.

SPECIFICATION forming part of Letters Patent No. 476,830, dated June 14, 1892.

Application filed February 13. 1889. Serial No. 299,693. (No model.)

.To all whom it may concern: connected through a supplemental coil ap- 50 Be it known that I, OLIVER B. SHALLEN- plied with a suitable commutator or with col- BERGER, a citizen of the United States, residlecting rings, according to the character of ing in Rochester, in the county of Beaver and the current required. The currents delivered State of Pennsylvania, have invented a new to the work-circuit are derived from this secand useful Improvement in Compensating. ond armature, and are either continuous or 55 Alternate-Current Dynamos, (Case No. 286,) alternating in direction, as may be required, of which the following is a specification. and accordingly as they are delivered through The invention relates to the class of eleca commutator or collecting-rings in a manner tric generators in which the field of force for well understood.

the armature is maintained by means of cur- For convenience of description the first- 6o rents, which may be generated either in the named armature will be referred to herein as machine itself or obtained from a separate the field-circuit armatureand the second as source. the work-circuit armature. The field-cir- The special objects of the invention are to cuit armature is constructed in the form of a provide a simple and efficient method of ob- Gramme ring in so far as the coils employed 5 taining the proper field of force for such genfor exciting the field-magnet are concerned; erators, whether designed to deliver continubut the core of this armature is constructed ous or alternating electric currents to a workwith a bridge connecting different points in circuit, and to secure such variation or reguthe core. These points are usually diametlation on the part of the field of force as may rically opposite each other. The supplemenbe required by reason of the variations in the t-al coils are wound upon this bridge-piece. current delivered to the work-circuit. In Lines of magnetic force developed by the some instances'it may be required that the field-exciting coils find their path through the 2 5 electro-motive force of the generator shall refield-magnet and armature in the usual manmain approximately constant, notwithstandner. The lines of force developed by curing variations which may take place in the rents traversing the supplemental coils of the amount of work being done. In other infield-circuit armature find a magnetic path stances it may be desired that the difference through the armature-core itself independ- 0 of potential at the terminalsof the machine ently of the field-magnets. Now it is evident should vary, according to some determinate that an effect may be produced upon the relaw relative to the increase of current, in order sultant lines of force out by the coils of the to compensate for an increased drop or load armature by varying the current traversing upon the circuit due to the transmission of the supplemental coils, from which it results 35 the increased current. The invention has that a certain definite effect may beproduced therefore this further object of compensating by variations in current flowing to the work- 8 5 for such varying difference of potential whencircuit. The manner in which this resultant ever Occasion m ir effect is availed of Willbe more fully described The general plan of carrying the invention connection with the accompanying draw- 40 into practice is as follows: Two armatures are ings, in wlnchplaced side by side upon an armature-shaft Figure l 1s a diagram showing, partly in and they revolve in the field of force estabsectlon, a side elevation of such portions of lished by a field-magnet common to both. a generator as are required to illustrate the The terminals of one of the armatures are invention, and Fig. 2 is an end View of the 45 connected with the field-magnet coils through field circuit armature. Fig. 3 illustrates a i a suitable commutator for rendering the curmodification 1n the construction of the field- 5 l rents continuous in direction, and it supplies circuit armature.

the current necessary to excite the field-mag- Referring to the figures, A represents the net. The terminals of the other armature are fieldnnagnet for establishing the field of force for two armatures B and B which are carried upon a shaft B. The armature B revolves in a field of force it s. It is wound with coils c, in which currents are generated for exciting the field-magnet. For this purpose the coils 0 may be connected with the commutator (Z in any convenient well-understood manner for rendering the currents generated therein continuous in direction. brushes d and (Z are connected with the terminals of the field-magnet coils a. The ar mature B may be of the type known as the Gramme ring, or other suitable well-known construction may be adopted, provided it is adapted to be employed in themanuer herein described. The second armature B revolves in the field N S. It may be of any suitable well-known character. Thathere shown consists of a so-callet druiii-armature, wound with coils 0 The current required for supplying a work-circuit, to which the conductors L and L lead is derived from the armature B For this purpose the terminals of the coils are connected with two contact-rings E E and the conductors L L are connected through suitable brushes 0 and c with the respective contactrings. A suitable commutator may replace the rings 6 0 when currents continuous in direction are desired upon the work-circuit.

It is evident that unless further provision were made the field of force established by the field-magnet would remain approximately constant, whatever variations might occur in the current delivered to the work-circuit from the armature B It" now it is desired to cause the field of force to vary in some manner dependent upon the variation of current required by the work-circuit, an additional variable force is required. This is secured by means of a second winding 0 applied to the armature B. This winding 0 is connected in series with the coils c or receives a determinate proportion of the current delivered by the coils 0 The coils are wound upon a bridge I), constituting a portion of the core of an armature B. This bridge connects two points diametrically opposite in the annular portion of the core B, and its position is so related to the winding and connections of the coil 0 of the armature B that the impulses generated by the revolution of the armature I) tend to establish lines of force through the cross-bar b and thus through the two sides of the annular portion of the core of the armatu re B, when the latter armature is in certain definite determined positions with reference to the field-magnet. With each semi-revolution'of the armature B, in the case of a twopole machine, there is a reversal in the direction of the current or impulse transmitted from the coils 0 through the coils 0 so that the direction of polarization of the bridge Z) produced by such currents is always in the same direction in space, but reversed with reference to the bridge itself. The lines of The polarization produced in the armature-core by reason of the coils c find their path through the two opposite halves b b of the armaturecore without being compelled to traverse the field-magnet.

The principal effects produced by these lines of force are as follows: The coils 0 receive current primarily by reason of the lines of force which are established by the fieldmagnet and which they are caused to cut by the revolution of the armature. It is well known, however, that a current may also be produced by maintaining two coils, themselves stationary, and establishing lines of force through such coils. The lines of force established by currents traversing the coils e do this, traverse the coils c, and thus in turn tend to develop currents therein. The direction of the currents thus developed with reference to those originally established by rea' son of the coils cutting the lines of force established by the field-magnets may be determined by the relative positions of the armature B and the bridge I). If it is desired to cause the current developed in the field-magnet coils to increase with an increase of current upon the work-circuit, then the positions are such as to cause the lines of force developed by the currents traversing the coils c" to aid in effect the lines of force established by the fieldmagnet in developing currents in the coils o. By reversing the relative windings of the coil 1) this effect may be reversed, and anyintermediate effect may be obtained by relative changes in the positions of the two armatures, as is evident. It should be noticed, however, that the resultant current produced is not due alone to the two causes mentioned, but a third effect must be considerednamely, that pro- (1 uced in the coils c themselves by theirchange of position with reference to-the field of force a sfor it is evident that an eleetro-i'notive force will be developed in those coils by reason of their being caused to cut the lines of force of this field. The value of this electromotive force is dependent both upon the proximity to the field-magnet and the number of convolutions in the coil 0 and it may be made to assist or detract from the current normally developed in the coil 0, as required.

.The construction of the armature B and its core may be variously modified as found convenient. Thus in Figs. 1 and 2 it is shown as having its ends in actual magnetic contact with the annular-portion of the armature, but cut away slightly. It may, however, be entirely separate from the annular portion, as shown in Fig. 3, or it may not be cutaway. In case it is entirely separated, as shown in Fig. 3, then it may be held in place by braces g, of brass or other non magnetic material. In

practice, however, it is usually desirable that it should be in magnetic contact, and that its cross-section should not be sufficiently great to allow too free a path for the lines of force developed by the field-magnet, for otherwise IIO it would detract to too great an extent from the lines of force traversing the annular portion of the armature.

By varying the position of the bridge I) and the relative position of the armature B and the amount of iron in the bridge I) and the winding of the same numerous diiferent resultant effects may be produced upon the current delivered by the machine, all of which, however, follow from the organization which has been described and will be evident to those skilled in the art without more detailed explanation.

I do not herein claim an electric generator in which both sets of armature-coils are wound upon one and the same core.

I claim as my invention 1. The combination, with a field-magnet, of an armature revolving in the field of force established thereby, a second armature, coils for establishing a field of force therefor, receiving currents from the first-named armature, a magnetic bridge-piece between points of opposite polarity in the core of the firstnamed armature, and supplemental coils Wound upon said bridge-piece.

2. The combination, with the field-magnet and two armatures revolving within the field of force established thereby, of a commutator through which currents are delivered from one armature t0 the coils of the field-magnet for exciting the same, a bridge-piece applied to the first-named armature, having its poles directed to points of normally-opposite polarity in the armature-core, supplemental coils wound thereon and connected in series with the coils of the second armature, and a commutator or collector constituting the terminals of the coils of the second armature.

3. An armature for electric machines, con- 0 sisting of an annular core, a bridge-piece directed to points diametrically opposite in said core, main exciting-coils upon the annular portion of said core, and supplemental coils wound upon the bridge-piece, substantially as 5 described.

4. An armature for electric machines, con sisting of an annular core, a bridge-piece directed to points diametrically opposite in said core, main exciting-coils upon the annular 5o portion of said core and supplemental coils wound upon the bridge-piece, a field-magnet excited by currents delivered from the firstnamed coils, and an independent source of current for the second-named coils. v

5. An armature for electric machines, consisting of an annular core, a bridge-piece directed to points diametrically opposite in said core, said bridge-piece being narrowed at its ends and in magnetic contact with the annu- 6o lar core, main exciting-coils upon the annular portion of said core, and supplemental coils wound upon the bridge-piece, substantially as described.

In testimony whereof I have hereunto sub- 6 5 scribed my name this 12th day of February,

OLIVER B. SIIALLENBERGER.

Witnesses:

CHARLES A. TERRY, W. D. U PDEGRAFF. 

